Blog

Guides and research on GitHub Actions, CI/CD, and AI code review
from the team building Tenki's runners, code reviewer, and agent sandboxes.

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CI/CD

Sticky disks keep your GitHub Actions caches warm between jobs

Tenki sticky disks keep dependency and compiler caches on a disk that follows the cache key, so jobs start warm without restoring a tarball.

Sep 29, 20267 min read

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CI/CD

How to benchmark GitHub Actions runners fairly

Compare CI runners on the same YAML, warm caches and repeated runs, measure cost per job instead of rate per minute, and see what our benchmark shows.

Sep 22, 202610 min read

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CI/CD

Sign and notarize macOS and iOS builds in GitHub Actions

Import a .p12 into a temporary keychain, install profiles, notarize with notarytool or use fastlane match, without leaving signing keys on the runner.

Sep 22, 20269 min read

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CI/CD

GitHub Actions cost optimization: how to cut your CI bill

Reduce GitHub Actions costs with runner right-sizing, caching, concurrency controls, workflow audits, spend alerts and a lower per-minute rate.

Aug 5, 202614 min read

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CI/CD

Self-hosted GitHub Actions runners: ARC, security, and cost

How self-hosted GitHub Actions runners register and autoscale with ARC, an 8-point hardening checklist, and the operational work you take on.

Jul 31, 202612 min read

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CI/CD

Copilot code review cost: AI credits plus Actions minutes

Copilot code review on private repos bills AI credits and GitHub Actions minutes. What each review costs, how to measure it, and which runners it can use.

May 22, 20268 min read

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CI/CD

The hidden CI tax of AI coding agents

AI coding agents open more PRs and push more often, and every push runs CI. How to model the extra cost, measure the agent share, and cut it.

Apr 8, 202610 min read

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CI/CD

Lint GitHub Actions workflows with actionlint: setup, config and CI

Install actionlint, read its errors, set custom runner labels in .github/actionlint.yaml, and run it in CI with problem matchers, reviewdog or pre-commit.

Mar 28, 202612 min read

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CI/CD

Monorepo CI with GitHub Actions: selective builds done right

Run only the CI jobs a change affects, using path filters, Turborepo and Nx affected builds, dynamic matrices, required checks and runner sizing.

Mar 6, 202617 min read

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CI/CD

Reusable workflows vs composite actions in GitHub Actions

When to share GitHub Actions config as a reusable workflow or a composite action, covering secrets, runners, logs, nesting limits and versioning.

Feb 6, 202614 min read

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CI/CD

GitHub Actions caching strategy: dependencies, builds and Docker

How the GitHub Actions cache matches keys, scopes and evicts entries, and how to cache npm, pnpm, Go, Python, Rust, Turborepo and Docker layers.

Jan 16, 202616 min read